In the summer of 2004, Zuckerberg and Sean Parker, who would briefly be president of the site, turned up at the San Francisco home of Peter Thiel on the hunt for an investment in what was then a barely known start-up. They walked away with $500,000 and left Thiel with a stake in a site that, with under 1m users, was in need of a friend. Seven years on and Thiel's stake is worth closer to $2bn.

Last week he was announced as one of six Facebook billionaires named on the annual Forbes list of the global super-rich.

But don't worry, you can grab a slice of the fortune. Thiel is donating money to help someone establish a sea city - yes, somewhere at least 50 people can live off the coast - by 2015. Or, if you're under the age of 20, you can apply to him for a grant of up to $100,000 should you have a great business idea. Zuckerberg's character was the star of the Oscar-winning film The Social Network, but scriptwriters' interest must have been pricked by Thiel's story.

Entrepreneur, futurologist, hedge fund manager, philanthropist, investor and writer - in an age of ever greater specialisation, the 43-year-old is moving at increasing speed in the opposite direction. "I do think there is something to be said for being a generalist in our society," Thiel said. Reversing the ageing process, robotics, artificial intelligence and human rights are all fields that The Thiel Foundation is using his cash to pursue.

Thiel always enjoyed going against the grain. As a student of philosophy at California's Stanford University, he co-founded The Stanford Review, a paper that railed against political correctness. Contrarians can, of course, be easily dismissed. That's less easy when some of their bets have reaped fortunes. Thiel himself is clear on the subject of money. "It would be one of the biggest mischaracterisations that we're doing this primarily as a way of making money," he says.

He first made plenty of it co-founding online payments company PayPal in December 1998 with Elon Musk and Max Levchin, whose parents had emigrated from the Ukraine to the US. By 2002 it was on the Nasdaq in the first big flotation after the September 11 terrorist attacks. Before the year was out eBay had swallowed it in a $1.5bn deal that is estimated to have netted Thiel more than $50m. So what did he learn from the PayPal chapter? "The big lesson people learnt existentially is that it's hard but doable. That's a good mindset with which to approach most problems."

The temptation is to be cynical when someone who is very wealthy says what they do is not really about the money. It feels a bit like a football manager saying it's all about the beauty of how the team plays, not whether they win or lose. But such an approach would be to neglect something that seems core to Thiel. At PayPal, he and Levchin talked about their online payments system as creating a new world currency free from government control. Armed with a definition of entrepreneur that includes - but isn't limited to - making money, it becomes clearer why Thiel took a bet on Zuckerberg's then little-known start-up.

"In many ways, Facebook is exhibit A," he explains. "If it had been run by people trying to make money they would have sold it for $1bn in 2006 to Yahoo!. That was a much lower priority than building a business to change the world."

Facebook is shaping the future, but for some the valuation of the site is beginning to echo the dotcom bubble of the late 1990s. 2011 opened with a controversial investment by Goldman Sachs that attached a $50bn price tag to the site that Mark built. That's been heading north on the secondary market on which Facebook shares can be traded. Sir Martin Sorrell, the founder of advertising giant WPP, warned this week that the value now given to the likes of Facebook is marked by some "speculative froth".

While admitting that there's "not much I can say on the subject that won't sound biased", Thiel ventures that "the current valuation is about one third of Google. If you think about what it [Facebook] is doing to change the world there's a decent argument that it's worth as much as Google."

You discover that Thiel, who was born in Germany but grew up in California, doesn't much like the company that Sergy and Larry built. The world's biggest search engine was truly innovative, he says, but is now more of a bet against developing new ways of navigating the web. Ditto IBM, Dell, Microsoft and Oracle. Just because a company pioneered a fundamentally disruptive technology doesn't mean they always will.

"Facebook has been the big breakthrough technology company of the last seven to eight years," Thiel believes, before adding "that the very odd thing about Facebook is it is so singular. Its specific success is masking a general failure."

Although it began in a university dormitory on the other side of America, Facebook is the latest flowering of Silicon Valley. The electic mix of entreprenuers, investors and engineers that call the area on the edge of San Francisco home proved a perfect incubator. Just as it had to Google, Apple, SunMicrosystems and many before that. Beyond the world's financial capitals, it's somewhere most people could locate on a global business map. It was also, of course, the backdrop to the birth of PayPal.

That doesn't stop Thiel nipping at the hand that helped feed him. "I still think that Silicon Valley has more innovation than anywhere else in the world. It has not been enough to move the dial," he explains. "I do think it's odd that the internet and the mobile internet are really the only areas that people have been focused on." Even so, it remains an area of focus for Thiel. Founders Fund, a venture capital firm that he co-founded in 2005 with two ex-PayPal colleagues, has scored some significant successes investing in this area. One investment, for example, Ironport, which develops email and security software for the web, was snapped up by Cisco in 2007 for $830m. Powerset, a business fashioning new technology for search engines, was bought by Microsoft for an estimated $100m.

If Thiel is prepared to point out what he sees as the limitations of Silicon Valley, he's scornful of a lack of innovation beyond computing power and the web. "Computer technology and the internet in particular has been the one dramatic exception in the past four decades in what has otherwise been stagnation." As the upheaval in North Africa keeps oil prices above $100 a barrel and threatens to send them higher, a lack of alternatives to crude is one example he cites. "The reality is that if there were no fundamental shortages, then these tensions [in Libya] would not be so destabilising," Thiel argues. "It frequently gets misinterpreted as a political crisis not a resources one."

Having made his fortune from innovating on the web, Thiel's central focus now appears on spreading that approach. He's most animated when he's wearing two hats: the investor and the thinker. They don't always sit comfortably. It's hard, for example, to see seasteading - the ambition to create offshore cities - or working to extend human life expectancy providing a quick return. During an event at San Francisco's Palace of Fine Arts last December, Thiel admitted one reaction people have to some of the technologies he's funding is "a lot of the stuff sounds really strange".

To understand why it doesn't to Thiel, requires a look at his map of the world. First up, a distinction between globalisation and technology. "Globalisation basically means taking things that work and extending them," he says. "Technology means doing something very, very new."

Warming to the theme, he argues that "all emerging markets are doing is copying. For the developed world, for countries like the UK, the US, western Europe and Japan, it will take more for people's living standards to be meaningfully better in 20 years." Rapid thoughts follow: the next big breakthroughs in technology will come from the West; a level of austerity will remain for many until they're made - and it's on a horizon of decades, not years, that people need to think.

"There's way too much talk of the short-term economic cycle - do we get a W, or a W-shaped recovery? There's far too little on the long-term question of what the economy will look like." Investors in Clarium Capital, the hedge fund Thiel started, may have wished he had paid more attention to the short-term horizon. Clarium correctly bet that the dollar would rise as would oil prices but, according to investors, got the timing of the bets wrong. Its assets have reportedly fallen by 90pc since 2008 and its New York office has closed. Thiel says that the fund had a good record before the past two challenging years and says he doesn't plan to stop making such bets.

Indeed, he insists it's in thinking about the intersection of macro economics and globalisation, on the one hand, and technology on the other, is where answers to the world's problems will come from.

"The sense we have is that we're in an emergency. We're not in a normal holding position," says Thiel. The PayPal co-founder has made millions from the disruptive technology of the internet. Whether his quest for new technologies offers matching financial rewards, will depend on whether or not his diagnosis becomes more or less relevant to the West.